1. Field of the Invention
The present invention deals with the field of inserts which are formed of material harder than the base material whenever the standard base material is not of a proper material to form lasting means of securement of external elements thereto. In particular, when utilizing plastic, rubber, wooden or certain thin metal materials, it is desirable to place metal inserts therein to provide means for securement thereto.
The present invention provides an insert which is threaded on the interior thereof and which is particularly adaptable to be secured within soft base materials which are molded to form the desired configuration. The molding operation can be performed in any of the conventional manners such as injection or compression molding, etc. With such designs it is necessary that the molding process include the threaded insert itself as a portion of the mold such that the base material is molded about the threaded insert during the formation of the basic part itself.
With such configurations a problem has arisen especially with respect to open bottomed inserts since the soft material such as plastic when under pressure during molding will be urged to seep around the narrow contact points between the ends of the threads and the pin which is positioned within the central area of the threaded insert during the molding process.
2. Description of the Prior Art
In currently used configurations of threaded inserts which are usable in molded base materials a champfered edge is utilized at the point of intersection between the open ended insert and the pin which is held therein during molding of the part. This champfered edge actually tends to increase the amount of seepage by concentrating the pressure along a narrow area rather than attempting to prevent seepage of the plastic material under pressure by the narrow ended threads. A similar champfered edge is used currently at the intersection between the uppermost edge of the outer surface of the threaded insert and the mold position thereagainst or the head of the pin which is positioned thereagainst. In either configuration the champfered edge serves to increase the amount of flowby of base material being molded under pressure thereagainst. In order to make sure that the threads are clean with such champfered edge designs it is necessary to perform an additional step of cleaning the threads by the passing of a threaded male member therein after the formation of the molded part. This is a costly and time-consuming operation which has been rendered unnecessary by the design of the present invention.